Trois résumés seront présentés au 1er congrès CLM.
Lors du 1er congrès du CLM, Mariana présentera ses résultats ce dimanche matin (11 février). Dr Rose y présentera aussi vendredi. Deux posters seront aussi présentés.
Publications connexes
Christopher F. *Rose, Rafael Ochoa-Sanchez, Mélanie Tremblay, Marc-André Clément, Christopher F. Rose.
Hepatic encephalopathy (HE) is a neuropsychiatric syndrome, a major complication of chronic liver disease (CLD/cirrhosis). With an increasing prevalence of obesity-induced cirrhosis and evidence linking blood-derived lipids to neurological impairment, we hypothesize that obesity increases the risk, severity and progression of HE. AIM: Development of an animal model of cirrhosis and obesity to investigate the synergistic effect of obesity and CLD on the development of neurological impairment and HE. M&M: Animal model of CLD and HE: 6-week bile-duct ligation (BDL) rats, as well as Sham-operated controls, were used. Inducing obesity: High-fat diet (HFD) was given for 3 weeks before BDL or Sham surgery. Groups: 1. Obese-BDL rats received HFD for 3 weeks pre-BDL and regular diet (RD) for 6 weeks post-BDL; 2. Lean-BDL rats received RD pre- and post-BDL; 3. Lean-Sham rats received RD pre- and post-Sham surgery. Behaviour: Recognition memory, motor coordination and muscular strength were assessed before surgery, as well as 3 and 6 weeks post-surgery using the novel object recognition, rotarod and grip-strength tests, respectively. Body-composition (echoMRI): Fat vs. lean mass and free water (ascites) were also monitored. RESULTS: Before the surgery, body weight (BW) and fat mass of rats on HFD (Obese-BDL) were increased in comparison to rats on RD (Lean-BDL and Lean-Sham). 3 weeks after surgery, BW, fat mass, lean mass and free water were increased in Obese-BDL rats vs. Lean-BDL rats. Long-term memory was reduced in Obese-BDL, but not in Lean-BDL, vs. Lean-Sham rats. 6 weeks after surgery, similar to Lean-BDL rats, Obese-BDL rats lost BW, fat and Lean mass, while free water increased vs. Lean-Sham rats. Motor coordination, forelimb strength and long-term memory were impaired in Obese-BDL rats in comparison to Lean-BDL or Lean-Sham rats, whereas hind-limb strength and short-term memory were impaired in both Obese- and Lean-BDL rats, compared to Lean-Sham rats. CONCLUSION: HFD induces obesity features in healthy non-cirrhotic rats. Such effects are maintained in cirrhotic-BDL rats. Obesity also accelerates the accumulation of free water in cirrhotic-BDL rats. Interestingly, some neurological impairments are detected in Obese-BDL but not in Lean-BDL rats (long-term memory), while others are exacerbated (motor coordination, forelimb strength). This new animal model of CLD and obesity suggests a synergistic effect, which accelerates and worsens the disease-associated abnormalities observed in CLD and HE. Thus, obesity-induced cirrhosis in patients may result in more complex neurological
Mariana Oliveira, Mélanie Tremblay, Christopher F. Rose.
The liver plays a major role in regulating ammonia levels in the blood. Therefore, in liver disease the loss of hepatic function leads to hyperammonemia and increased brain ammonia and consequently hepatic encephalopathy (HE). Ammonia-lowering strategies remain the mainstay therapeutic strategy. Ammonia, both as an ion (NH4+) and gas (NH3), easily crosses all plasma membranes, including the blood brain barrier (BBB); the interface between the blood and the brain. Glutamine synthetase (GS), an enzyme which in the process of amidating glutamate to glutamine removes ammonia, plays an important compensatory role during liver disease. GS is expressed in muscle and brain (primarily in astrocytes) but has never been thoroughly explored in the BBB. Therefore, the aim is to evaluate GS expression in endothelial cells of the BBB. Using primary rat brain microvascular endothelial cells (ECs), the presence of GS was assessed using rtPCR, western blot, immunohistochemistry and activity assay. Furthermore, we isolated cerebral microvessels (CMV) from the frontal cortex of naïve rats and measured GS expression by western blot using brain lysates as positive control and by immunohistochemistry (co-localized with caveolin-1 (marker for ECs). In addition, to understand the effect of ammonia on GS, ECs were exposed to 1mM of ammonia chloride for 48h. Finally, ECs were subjected to plasma from bile-duct ligated (BDL) rats (model of chronic liver disease) or sham-operated controls. We have characterized this BDL model and found both systemic oxidative stress and inflammation, in addition to hyperammonemia. ECs expressed GS mRNA, protein and activity. However, expression of GS was lower compared to brain lysate control samples (p<0.05). GS expression in CMV showed similar results to brain but GS activity was less (p<0.05). Using immunohistochemistry, GS was detected in ECs and in vessels of brain from naïve rats. When cells were submitted to ammonia, an increase in GS activity was demonstrated (p<0.05). However, when exposed to conditioned medium from BDL rats, GS was decreased when compared to sham-operated controls (p<0.01). These results demonstrate for the first time that GS is present in ECs in both in vivo and in vitro. The lower expression of the enzyme compared to that found in the brain, could explain why GS has never been reported in these cells. Interestingly, ammonia stimulates GS in endothelial cells, but its activity is decreased in the presence of other pathogenic factors in plasma from cirrhotic rats such as oxidative stress and inflammation. We speculate that a downregulation of GS allows for a faster and easier entry of ammonia into the brain and therefore may be implicated in the pathogenesis of HE. We anticipate increasing GS in ECs of the BBB could become a new therapeutic target for HE
Christopher F. *Rose, Cassandra Picinbono-Larose, Annie Lamoussenerie, Mélanie Tremblay, Catherine Vincent, Geneviève Huard, Christopher F. Rose, Chantal Bémeur.
Background: Malnutrition is an important prognostic factor potentially influencing clinical outcome of patients suffering from chronic liver disease (CLD; cirrhosis) and may increase the risk of developing other complications including hepatic encephalopathy (HE). Malnutrition in cirrhosis may also affect patient’s functional status and health-related quality of life (HRQOL). Management strategies focussing on nutritional status in relation to complications of cirrhosis are an unmet clinical need. We hypothesize that sub-optimal nutritional status in cirrhotic patients increases the risk of developing HE and decreases HRQOL. Purpose: The primary purpose is to evaluate the impact of nutritional status on health-related quality of life in cirrhotic patients. The secondary purpose is to ascertain the presence of hepatic encephalopathy and examine its relationship with nutritional status and HRQOL. Method: Hospitalized and outpatients (CHUM’s Liver Unit, Montreal, Canada) with cirrhosis as well as non-cirrhotic (NC) patients were assessed for 1) Nutritional status (Subjective Global Assessment (SGA)); 2) HE (presence or history); 3) HRQOL (Short-Form-36 (SF-36) questionnaire). Results: 50 cirrhotic patients (72% men) of various etiologies, Child-Pugh (15A, 7B, 18C, 10 unknown), mean age 56±12 as well as 18 NC patients (33% men, mean age 42±15) were included. SGA analysis revealed that 34% of cirrhotic patients were malnourished whereas 12% of cirrhotic patients were diagnosed with HE at time of recruitment and 37% had a history of HE. Among malnourished CLD patients, 18% were diagnosed with HE. CLD malnourished patients showed a decreased HRQOL compared to well-nourished CLD patients (p<0,01). Moreover, HE had an impact on HRQOL as cirrhotic patients with a history of HE episode(s) showed decreased physical functioning (p=0,024) and role limitations due to physical health (p=0,002). Interestingly, when compared to NC patients, CLD patients displayed a lower score in physical functioning (p<0,0001) and general health (p=0,027). Conclusion: Our data suggest that poor nutritional status does negatively influence HRQOL in cirrhotic patients but is not associated with HE. However, history of HE episode(s) does impact on HRQOL among this population. Therefore, identifying malnourished patients is of great importance and interventions for treating malnutrition remains an unmet clinical need.
